Symptom of Bacterial leaf blight

1. ‘Kresk’ occurs in early stage (plant withers and dries up), in later stage blightining starts from the tip of the leaves to the base, straw turned yellow, partially filled grains.

Management

1. Use balanced fertilizer dose.

2. Drain out excess of water.

3. Use resistant varities like Sawa masuri, Bambleshwari.

1. Spraying with copper fungicides (Blitox 0.3%) alternately with Streptocycycline (250 ppm).

2. Application of moderate dose of nitrogenous fertilizer (80 kg/ha) and use of wider spacing (30 x 15 cm) .

3. Growing resistant varieties to the disease .

Greenish-yellow strips appear along the leaf margins and extend both lengthwise and breadthwise. The leaf starts drying from the tip, becomes white in severe cases and dries up completely. The disease sometimes attacks the freshly transplanted seedlings which start wilting and in a few days the whole clump dries up. The bacterium perpetuates through seed, rice straw, and roots of non-host plants during the off-season. In order to mitigate the losses, adopt the following measures :

No single effective control measure is available. Therefore, integrated measures are suggested.
Use of resistant cultivars
Use of resistant cultivars is the most economic and environment safe strategy for the management of bacterial blight disease. Although several BB R genes have been identified and characterized, the effectiveness of these genes varies due to difference in virulence profile of the pathogen in different geographical regions. In India, a large no. of rice varieties has been released showing resistance /tolerance to bacterial blight.
Chemical Control

• Lateritic and alluvial soil favour more bacterial blight diseases. 
• Water logging condition encourages disease development. 
• Excessive use of N fertilizers from tillering stage to maximum tillering stage encourages disease development. 
• Growing of the crop under shade favours disease development.
• Pruning of leaves at the time of transplanting favours disease development.

The causal organism is the bacterium Xanthomonas oryzae pv. oryzae (Ishiyama) Swings et al. According to the new classification system, it has been placed in:
Phylum : Proteobacteria
Class : Gyammaproteobacteria
Order : Xanthomonadales
Family : Xanthomonadaceae

• Water soaked lesions move from tip downwards on the edges of leaves.

• Gradually symptoms turn into yellow and straw coloured stripes with wavy margins.

• In early morning in humid areas yellowish, opaque, turbid drops of bacterial ooze may be seen.

• In Kresek (wilt) phase, leaves roll completely, droop and plants die completely.

1. The extent of yield loss depends on the growth stages of the crop at which it is infected, the level of susceptiblility of the cultivar, season, climatic condition and level of nitrogen fretilizer applied.

2. The damage may be due to partial or total blighting of the leaves or complete wilting of the affected tillers leading to unfilled grains.

1. Bacterial leaf blight of rice caused by Xoo is one of the most destructive diseases of rice in majority of the rice growing countries especially in Asia.

2. Though the disease has been known in Japan since 1884, its bacterial nature was established in 1922. Subsequently the disease was reported from most of the rice growing countries.

- Burn the stubbles. - Use optimum dose of fertilizers

. - Avoid clipping of tip of seedling at the time of transplanting.

- Avoid flooded conditions.

- Remove weed hosts.

- Grow resistant cultivars like Birsamati, Birsa Vikas Dhan 110, Birsa Vikas Dhan 109, Hazaridhan, Sadabahar, Birsa Dhan 108, Shivam and Swarna showed resistance against bacterial leaf blight (BLB) of Rice.

- Seed Treatment: with Carbendazim 50 WP or Beam (Tricyclazole) @ 2 gm/kg seed.

- Foliar spray: Make solution of 2 gm Streptocycline in 10 lt water (0.02%).

1. The bacterium Xanthomonas oryzae pv. Oryzae is strict aerobe, gram negative, non spore forming, rod shaped with size ranging from 1-2 x 0.8-1.0um with monotrichous polar flagellum of 6-8 um. The bacterial cells are capsulated and are joined to form an aggregate mass. Colonies are circular, convex with entire margins, whitish yellow to straw yellow later and opaque.

1. Use seed from disease free crop.

2. Treat the seeds by soaking it for 12hrs in a mixed solution of streptocycline(0.15%) and wetable Ceresan (0.05%) followed by hot water treatment at 52oC-54oC foe 30 minutes.

1. The bacterium induces either wilting of plants or leaf blight. Wilting syndrome known as 'Kresek' occurs sporadically in the fields causing serious damage.

2. Bacterial leaf blight commonly occurs within 3-4 weeks after transplantation of the crop. Kresek results either in the death of whole plants or wilting of only a few leaves.

1. Causal Organism: Xanthomonas compestris pv. Oryzae.

2. Bacterial blight is a monsoon disease and its incidence and severity is very much influenced by rainfall, number of rainy days, and susceptibility of the cultivar and nitrogen fertilizer application.

3. Severe epidemics recorded in 1979 and 1980 in northwestern India, reducing the grain yields drastically.

Chemical control of Bacterial Blight,

1. Seed treatment with streptocycline @ 0.5 g/lit. Prepare 50 liter water solution using the streptocylcine and soak for 24 hrs, dry under shade and use for sowing.

2. Foliar spray with streptocycline @ 0.4 g + copper oxychloride @ 1 g /lit of water at 50 DAT and at seed setting stage.

3. Copper fungicides containing 50% copper oxychloride have been found to be quite effective.

4. Agrimycin-100 has also been reported to be effective against bacterial blight.